1. Field of the Invention
The present invention relates to a communication apparatus, and more particularly to a communication apparatus connected to a line together with a telephone set for communicating through the telephone set and communicating data by switching line connection between a telephone communication path and a data communication path.
2. Related Background Art
In the past, in this type of apparatus such as a facsimile machine, communication control has been done in accordance with various signals received from a telephone line. Those signals include a facsimile call signal, a tonal signal, a dial tone (DT) signal and a busy tone (BT) signal. Those signals are usually detected by different systems by independent circuits because of differences of termination conditions of the lines and magnitudes of powers.
In the prior art apparatus, it is necessary to prepare separate circuits for different types of received signals. Thus, it is difficult to reduce the cost and size by reducing the number of parts. Further, software is complex because separate software control circuits are required.
A technique relating to the signal reception is disclosed in U.S. Pat. No. 4,837,806.